Shuffle icon in Music app on Mac mini appears fuzzy

Hi, out of interest why does my shuffle icon on Music go fuzzy every now and then [Mac 2024 mini - Tahoe 26.1]? When I have it selected it sometimes has a 'halo' around the red criss-cross which comes and goes. All seems to work (so far as I know), I just wondered why. I have a mix of my own music and downloaded music showing. Is it the Apple Music downloads 'catching up'?